Hosea 1:3

‘So he went and took Gomer the daughter of Diblaim, and she conceived, and bore him a son.'

In obedience to YHWH Hosea married Gomer, the daughter of Diblaim, and ‘took her' (married her and had sexual relations with her), with the result that she conceived and bore him a son. There is no hint here of any personal moral defect in her. The concentration is on the children. We should, of course, remember that this bearing of three children, including their weaning, would take up a number of years so that this was intended to be a protracted message, unfolded over a longish period, which was to arouse deep interest among the godly as they took in its message, and may well have stirred the interest of many of the ungodly. God was giving Israel time to repent.

There is no obvious significance to the name Gomer (the name means ‘completion'), even though great efforts have been made to try to form one. But all such attempts to find one are pure speculation. She was simply necessary for the production of the children whose names would bear a message to Israel.